Bidirectional gasket having water energizing pockets

ABSTRACT

A bidirectional gasket providing a water-tight seal between an opening in a manhole assembly and a pipe extending into said opening, comprises a T-shaped anchoring portion for embodiment in a manhole opening. A substantially A-shaped pipe engagement portion is joined to the anchoring portion by a slender connecting web facilitating bending of the gasket. The A-shaped portion has &#34;legs&#34; and recesses which form water pockets preventing water from entering. The durometer of the gasket material enhances the water-tight seal of the legs with increasing water pressure. The pipe engaging portion accommodates a greater outside pipe diameter compared with conventional connectors due to reduced volume, by providing voids within the connector together and a lower durometer of gasket material. The gasket has enhanced ability to accommodate diameter deflection or ovation in rigid and flexible pipe materials. The A-shaped profile allows for greater angular deflection and/or pipe misalignment compared with conventional connectors. The gasket apex has a recess to locate the voids which, in addition to enhancing mechanical softness of the gasket, also provides the ability to increase gasket compression by introducing a liquid filler into the voids. Tapered projections near the apex wipe the external periphery of a pipe upon insertion and also contribute to the compression of the nose portion of the connector. The gasket may be molded or formed from an elongated extrusion joined at its ends to form an annular gasket.

FIELD OF THE INVENTION

The present invention relates to gaskets for providing a water-tightseal between a manhole opening and a pipe extending into said openingand more particularly to a novel bidirectional gasket havingself-energizing water pockets which enhance the water-tight sealprovided by the gasket whereby the sealing pressure increases withincreasing water pressure and wherein the gasket design is capable ofaccepting pipe diameters over a wider tolerance than conventionalgaskets.

BACKGROUND OF THE INVENTION

Rubber connectors are typically utilized to provide a water-tight sealbetween an opening in a manhole assembly and a pipe extending into theopening. U.S. Pat. No. 4,159,829 assigned to the assignee of the presentinvention discloses a conventional bidirectional connector formed froman extrusion having a hollow, pear-shaped head portion integrally joinedto a T-shaped anchoring flange. The extrusion is cut to length andcurled to form a substantially right cylinder configuration with themating edges being joined. The pear-shaped portion deflects from aradially inward orientation upon insertion of a pipe. A single cavityextends through the head portion to provide the head portion with addedresiliency and provides moderate sealing pressure. U.S. Pat. No.4,508,355 assigned to the assignee of the present invention constitutesan improvement over U.S. Pat. No. 4,159,829 by providing a gasket ofsimilar shape having a plurality of internal cavities extendinglongitudinally through the head portion to provide the desiredresiliency while at the same time providing improved stability of gasketconfiguration which yields a stronger and more uniform seal around theexterior of the sewer pipe including portions of the surface which maybe significantly out-of-round.

The above designs nevertheless have the disadvantages of providing awater-tight seal which weakens as the water pressure applied to thegasket increases and which has very narrow tolerance limits with regardto the range of pipe outer diameter which can be accepted by a gasketthereby greatly increasing the number of gaskets required to cover alarge range of pipe outer diameters, typically from 4" to 84".

BRIEF DESCRIPTION OF THE INVENTION

The present invention is characterized by comprising a bidirectionalgasket which retains all of the advantages of gaskets of like design, aswere described hereinabove, for example, and which overcomes the abovementioned disadvantages as well as provided other advantages not foundin such conventional gaskets. The gasket of the present invention ischaracterized by comprising a T-shaped anchoring portion and asubstantially A-shaped or pear-shaped pipe engaging portion similar tothose found in conventional gaskets, as described hereinabove, forexample. As a departure from conventional design, the A-shaped portionis provided with recess near its wide end which defines a pair of legsthe extend away from the head portion and act as water seal flaps. Thewide end of the A-shaped portion is joined to the anchoring portion byan integral connecting web having a thickness which is significantlyreduced relative to the thickness of the adjacent anchoring portion theconnecting web greatly facilitating bending of the connecting web andhence the gasket.

The connecting web cooperates with the legs and recess in the A-shapedportion to form a pair of water pockets, one of which becomes activedependent upon the direction in which the gasket is deflected, toprovide a water-tight seal which increases an effectiveness with theincreasing water pressure imposed upon the gasket. The legs also providesignificantly greater body contact between the gasket and the pipe,further enhancing the water-tight seal.

The flexibility and compressibility of the gasket are increased throughthe use of voids in the head portion of the gasket. The gasket materialhas a durometer comparable with conventional gaskets of similar design,the durometer of the gasket also contributing to the effectiveness ofthe "water pocket".

The bendability, flexibility and compressibility of the gasket, inaddition to providing a good water-tight seal, also permit the gasket toaccommodate a wider tolerance range of pipe diameters.

The weight of the gasket is further reduced and the compressibility isthus further enhanced by the continuous openings or voids extendingaround the gasket and arranged within the A-shaped portion of thegasket, which voids are capable of being filled with a suitable liquid,in situations requiring reduced compressibility.

The tip of apex of the A-shaped portion is provided with a centeringgroove which serves to positively locate the internal voids, therebyserving as the means for guiding insertion of a hypodermic-typeinjection needle for penetration into the hollow region and insertion ofa suitable liquid for increasing gasket volume and reducingcompressibility.

A coupling web increases the gasket flexibility to such an extent thatthe gasket, in addition to providing a wider tolerance range for pipediameter, provides an effective water-tight seal for pipes whoselongitudinal axes are offset from desired alignment by an offset angleof as much as 15° as compared with a maximum offset angle of 10°obtainable when employing conventional gaskets of similar design.

In addition, integral tapered projections provided near the narrow tipof the A-shaped portion serve as "wipers" which wipe lubricant appliedto the external periphery of the pipe to facilitate coupling with thepipe, the wiping action further enhancing the pipe/connector seal. Theprojection performing the wiping action is ultimately compressed againstthe surface of the pipe.

OBJECTS OF THE INVENTION

It is therefore one object of the present invention to provide a novelbidirectional gasket for providing water-tight gasket/pipe seal which issuperior to that of conventional gaskets of similar design and which isaccomplished in a gasket of reduced volume and weight.

Another object of the present invention is to provide a novelbidirectional gasket having water pockets designed to enhance theeffectiveness of the water-tight seal with increasing water pressureimposed upon the gasket.

Another object of the present invention is to provide a novelbidirectional gasket having increased flexibility as compared withconventional gaskets of similar design through the employment of aconnecting web of significantly reduced thickness arranged between andintegrally joined with a T-shaped anchoring portion and an A-shaped pipeengaging portion.

Still another object of the present invention is to provide a novelbidirectional gasket for providing an enhanced gasket/pipe seal andcomprising a substantially A-shaped pipe engaging portion whose narrowend is provided with integral wiping projections for wiping lubricantfrom the pipe as it is inserted to further enhance the water-tight sealprovided by the gasket.

Yet another object of the present invention is to provide a gasketproviding a water-tight seal between a pipe and an opening in a barrierwall, said gasket having a head portion engaging the pipe and providedwith extending legs which significantly increase the contact areabetween the gasket and the pipe to further enhance the water-tight seal.

BRIEF DESCRIPTION OF THE FIGURES

The above as well as other objects of the present invention will becomeapparent from reading the accompanying description and drawings inwhich:

FIG. 1 shows a sectional view of a gasket embodying the principles ofthe present invention and in which a pipe has been inserted;

FIG. 2 shows a detailed sectional view of the gasket of FIG. 1 in theposition occupied by the gasket before insertion of a pipe;

FIG. 2a shows an enlarged sectional view of the water pockets providedin the gasket as shown in FIG. 2;

FIG. 3 shows a sectional view of the gasket which is useful inexplaining the effectiveness of the pipe/gasket seal provided by thewater pocket; and

FIG. 4 shows a detailed view of the tip portion of the gasket.

DETAILED DESCRIPTION OF THE INVENTION

Making reference to FIGS. 1 and 2, the gasket 10 of the presentinvention is preferably formed from a continuous extrusion of a suitablesynthetic elastomeric material.

The extrusion shown in cross-section, is comprised of an A-shaped headportion provided with a recess R at the apex or tip of its narrow end,as shown in FIG. 4. Tapered sides 12a and 12b terminate in a pair oflegs 12c and 12d at the wide end of the head portion opposite recess R.

The pair of integral projections 12e and 12f arranged on opposite sidesof the recess R serve as wiping members for wiping lubricant from aninserted pipe, as will be more fully described.

The gasket is formed of a suitable rubber or rubber-like materialselected to provide a gasket having a durometer of the order of 50-55which is comparable to conventional gaskets, for example, those gasketsof the type described in the aforementioned '355 and '829 patents.

The volume, weight and compressibility of head portion 12 is furtherreduced through the provision of cavities 12g and 12h which arepreferably symmetrically located with resepct to the aid of symmetryS-S' of the cross-section of head portion 12, axis S-S' extendingperpendicular to the axis of cavities 12g and 12h and extending throughthe mid-line of the anchoring portion and connecting web as will be morefully described below. The cavities 12g and 12h are substantiallycontinuous around the gasket.

Cavities 12g and 12h are preferably of different diameters, cavity 12hbeing larger than cavity 12g. The size and location of the cavities, inaddition to reducing the material present in the gasket to provide thedesired resilience, nevertheless provide lateral stability to thestructure which assures the maintenance of configurational integrity,causing the desired function of the gasket to be retained despite thelarge forces exerted upon the gasket by the pipe inserted therethrough.

The gasket is further comprised of a T-shaped anchoring portion whichincludes a neck portion 14 and an integral foot portion 16 which areadapted to be embedded into the cast material 22.

The A-shaped portion 12 is joined to neck portion 14 by an integralconnecting web 18 integrally joined to the wide end of head portion 12and the end of neck portion 13 remote from foot portion 16. Web 18 has athickness which is significantly reduced as compared with the thicknessof neck portion 14 to provide enhanced flexibility and bendability ofthe gasket as will be more fully described.

The wide end of A-shaped portion 12 is provided with a pair of curvedrecesses 12i, 12j shown in greater detail in FIG. 2a which, togetherwith connecting web 18 and legs 12c and 12d form a pair ofself-energizing water pockets P1, P2 which serve to increase theeffectiveness of the water-tight seal as the water pressure applied tothe gasket increases, as will be described more fully hereinbelow.

In order to form a gasket of the desired size and diameter, theextrusion is cut to a proper length and is formed into a circle with thefree ends of the gasket being bonded together to provide a ring-likegasket. The joining and bonding techniques utilized for forming thering-like gasket are conventional and may incorporate the techniquesdescribed in the aforementioned '355 and '829 whose descriptions areincorporated herein by reference thereto.

Although the gasket of the present invention lends itself readily toformation through the employment of an extrusion technique, it ispossible to mold the gasket, if desired.

The gasket is preferably embedded within a manhole assembly, forexample, by the use of conventional positioning rings, theaforementioned method and apparatus being described in theabove-identified '829 patent with particular reference being made toFIGS. 6 and 7 and the descriptive portions related thereto.

FIG. 1 shows the gasket 10 of the present invention installed in opening21 in sidewall 20 which may, for example, be the sidewall of a manholeassembly and more particularly, a manhole base cast, for example, from asuitable material such as concrete.

FIG. 2 shows a detailed sectional view of the gasket in cast material 22and in the undeflected position normally assumed prior to insertion of apipe.

FIG. 1 shows the manner in which pipe 24 is inserted within opening 21.Pipe 24 preferably, although not necessarily, is provided with a taperedright-hand end 24a which facilitates insertion of the pipe into theopening and the gasket. The outer periphery of pipe 24 is alsopreferably coated with a lubricant to further facilitate entry of thepipe into the gasket.

FIG. 1 shows the pipe after insertion, the pipe originally being movedfrom left to right, causing the gasket to undergo bending from theundeflected position shown in FIG. 2 to the deflected position shown inFIG. 1. The projection 12g permits easier coupling by allowing thelubricant to remain in the immediate area where the gasket and pipesurface meet. This ensures that the proper amount of lubricant remainspresent to prevent tearing or frictional wear of the gasket profileduring coupling. When the coupling action is completed, the lubricanttypically used in pipeline construction will actually create africtional bond between the gasket and pipe surface as the lubricantdisperses. In addition, the projection 12g is compressed between themain body 12a of the gasket and the pipe when the pipe is moved to itsfinal position.

The bending of the gasket serves to urge the legs 12c against pipe 24 tosignificantly increase the surface area contact between the gasket andthe pipe, especially when compared with the gaskets disclosed in the'829 and '355 patents.

Self energized water pocket P1, in addition to blocking water frompassing from the external side of side-wall 20 between the gasket andthe pipe, further provides a self-energizing function wherein thebuild-up of water pressure within pocket P1 applies an increasing forceupon head 12 and leg 12c, as shown in FIG. 3 causing the head 12 andespecially leg 12c to apply increasing pressure upon the surface of pipe24, with the result that the greater the water pressure, the better theseal between the gasket 10 and pipe 24. The increased surface contactbetween gasket and pipe due principally to the legs 12c, 12d alsocontributes significantly to the effectiveness of the water-tight seal.Also the likelihood that an imperfection in the pipe surface will createor cause a failure is greatly reduced.

Employing a gasket material having a durometer of the order of 50-55increases the compressibility of the gasket, enabling the gasket todeflect from the undeflected position to that of FIG. 2 to that shown inFIG. 1 and further enables the gasket flange 12c, for example, toexperience compression due to the build-up of water pressure within theself-energizing pocket P1. The durometer of the gasket, coupled with thevoids 12g and 12h, enables the gasket to accommodate a pipe diametertolerance range which is significantly greater than that of conventionalgaskets of similar design due to the reduction in physical volume andrubber durometer. In addition, the gasket flexibility accommodatesdiameter deflection and/or ovation in flexible pipe materials.

The profile of gasket 10 also accommodates greater angular deflectionand/or pipe misalignment as compared with conventional gaskets. FIG. 1shows the angle α of deflection which may be as much as 15° deviationfrom the desired longitudinal axis while maintaining a good water-tightseal. This compares very favorably with conventional gaskets of similardesign which provide a maximum deviation of 10°.

The legs 12c, 12d extend well beyond the head portion 12 and extend tothe opening 21 in wall 22 and preferably extend partially into annularrecesses in opening 21 as shown in FIG. 2. The leg 12c snaps away fromthe position shown in FIG. 2 upon deflection of the gasket. Thepenetration of the legs into opening 21 is chosen to maximize the lengthof legs 12c, 12d while preventing the legs from being locked in to thecast material and this prevented from engaging pipe 24.

The coupling pressure of the gasket (in the absence of water pressure ina water pocket) is comparable to conventional gaskets of similar designdue to the rubber durometer and overall volume while at the same timeproviding a good water-tight seal which increases in effectiveness dueto the self-energizing water pocket design described hereinabove.

The gasket of the present invention provides superior sealingcapabilities as compared with conventional gaskets of similar designwhile being of reduced size and weight thus significantly reducing thecost of materials and hence the cost of production. The gasket design,size, volume and durometer further enable the gasket to acclimate awider tolerance of pipe diameter, enabling, for example, gaskets of fourcross-sectional sizes to cover a complete range of pipe sizes from 4inches to 84 inches diameter pipe, as well as accommodating both rigidand flexible pipe.

A latitude of modification, change and substitution is intended in theforegoing disclosure, and in some instances, some features of theinvention will be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the spirit and scopeof the invention herein described.

What is claimed is:
 1. A bidirectional annular gasket for providing awater-tight seal between an opening in a barrier wall and a pipeinserted into said opening, said gasket comprising a ring of elastomericmaterial having a substantially uniform cross-section along itscircumferential length, said cross-section comprising a T-shapedanchoring portion including a radially-outwardly directed foot portionand a neck portion integral with said foot portion and extending atright angles and radially inward therefrom to form said T-shapedanchoring portion and a head portion extending radially inward of saidfoot portion for engagement with the exterior of said pipe;said headportion having a substantially A-shaped configuration defined by a wideend tapering to a narrow tip, with the wide end of said A-shapedconfiguration being positioned adjacent said anchoring portion and anarrow tip forming an apex of said head portion and, prior to insertionof a pipe, extending radially inwardly from and being remote from saidanchoring portion; the head portion, prior to insertion of a pipe, beingsubstantially symmetrical about a plane passing through the center ofthe head portion and aligned with said radial direction; the wide end ofsaid head portion being provided with a recess defining a pair of legsextending diagonally outward and away from the main body of said headportion; a connecting web joining said A-shaped configuration and saidanchoring portion and being integrally joined at a first end to the wideend of said A-shaped configuration substantially at midpoint of saidrecess and at a second end to a radially inward end of said neckportion; and said connecting web dividing said recess into a pair ofpockets on opposite sides of said web.
 2. The gasket of claim 1 whereinthe thickness of said connecting web, measured in a directionperpendicular to said plane, is less than the thickness of said neckportion measured in said perpendicular direction to facilitate flexingand bending of said connecting web upon insertion of a pipe into saidgasket when the diameter of the pipe is greater than the diameterdefined by the apex of said gasket head portion causing said gasket tobend in a region of said connecting web.
 3. The gasket of claim 1wherein .Iadd.said head portion is provided with first and secondcavities each of substantially circular cross-section and spaced fromone another in a radial direction to define a wall between said cavitiestransverse to said plane, each of said cavities extending substantiallycontinuously about the circumference of the gasket and said A-shapedportion is further provided with a recess at the tip of said A-shapedportion to facilitate location of said cavities and to facilitateinsertion of a hypodermic-type needle for insertion of a liquid materialinto at least one of said cavities to alter .[.the.]. compressibility ofthe gasket.
 4. A bidirectional gasket for use in forming a fluid-tightseal between a pipe and an opening in a barrier wall through which saidpipe passes, comprising:an annular member of elastomeric material havinga tubular head portion of a substantially A-shaped cross-section definedby a wide end and having tapering sides tapering to a narrow tip and afoot portion comprising a base flange portion and a neck portion ofsubstantial thickness integrally joined to a mid-region of said baseflange portion to form a substantially T-shaped anchoring portion forembodiment within a cast material forming said barrier wall; said headportion tapering sides being substantially symmetrical about a planepassing through a longitudinal axis of the said A-shaped portion; aconnecting web extending between said neck portion of said foot portionand the wide end of said A-shaped head portion; said A-shaped headportion having .[.a plurality of.]. recesses at the wide end thereof.Iadd.and arranged .Iaddend.on opposite sides of said connecting web anda pair of flanges, each extending diagonally away from its associatedrecess at an angle substantially equal to the angle formed by thetapering sides of said A-shaped cross-section, said recesses formingself-energizing water pockets to cause the flange of the associatedwater pocket which may be filled with water to exert a greatercompression force against an engaging surface of a pipe inserted throughsaid gasket as a function of increasing water pressure applied upon saidwater pocket; and said annular member being formed from .Iadd.a linearextrusion, .Iaddend.a length of said linear extrusion being curved andjoined at its ends to form said annular .[.ring.]. .Iadd.member..Iaddend.
 5. The gasket of claim 4 wherein the thickness of saidconnecting web is substantially less than the thickness of said neckportion to enhance the bending flexibility of said gasket.
 6. Th gasketof claim 4 wherein each of said recesses has a curved concave surfaceportion to facilitate the intimate engagement of its associated.[.flap.]. .Iadd.flange .Iaddend.with a pipe due to increasing waterpressure.
 7. A bidirectional gasket for use in forming a fluid-tightseal between a pipe and an opening in a barrier wall through which saidpipe passes, comprising:an annular member of elastomeric material havinga substantially constant cross-section comprising a tubular head portionfor engaging a pipe and a foot portion comprising a base flange portionand a neck portion of substantial thickness integrally joined to a midregion of said base flange portion to form a substantially T-shapedanchoring portion for embodiment within a case material forming saidbarrier .[.walls.]. .Iadd.wall.Iaddend.; said head portion havingtapering sides which are substantially symmetrical about a plane passingthrough a longitudinal axis of said head portion; a connecting webextending between said neck portion of said foot portion and said headportion; a pair of recesses provided in said head portion on oppositesides of said connection web for forming water pockets; said headportion having a pair of integral legs extending away from said headportion in a generally radially outward direction, each leg andconnecting web defining sides of an associated recess; and said waterpockets serving as water-tight enhancing means urging the leg of theassociated water pocket which may be filled with water to exert agreater compressive force against an engaging surface of a pipe insertedthrough said gasket as a function of increasing water pressure.
 8. Thegasket of claim 7 wherein the thickness of said connecting web issubstantially less than the thickness of said neck portion and said headportion to enhance the bending flexibility of said gasket.
 9. The gasketof claim 7 wherein the length of said legs is greater than the length ofsaid connecting web, said lengths being measured generally along a linepassing through the center of said connecting web.
 10. The gasket ofclaim 7 wherein .[.the.]. ends of said legs engage the opening in saidbarrier wall, prior to insertion of a pipe, and are adapted toselectively engage the pipe when the gasket is deflected due toinsertion of a pipe.
 11. The gasket of claim 7 wherein .[.the.]. ends ofsaid legs extend a small predetermined distance into annular recessesprovided in the opening in said barrier wall and are adapted toselectively snap out of said recesses when the gasket is deflected dueto insertion of a pipe.
 12. The gasket of claim 7 wherein said legssubstantially overlie said connecting web.
 13. The gasket of claim 7wherein said connecting web has a predetermined length, said recesseseach having a depth substantially equal to the length of said connectingweb.